Improved Differential Scanning Calorimetric Measurement Method for the Small Reaction Heat Capacities

Abstract

Abstract Heat capacities of the different rubber states are important features for the engineering calculation of rubber manufacturing. The heat capacity change Δcp due to the vulcanization process has been measured with a differential scanning calorimeter (DSC) only after reducing the standard error of a Δcp measurement under 5 J kg−1 K−1. For this purpose, we used sealed (up to 150 bar) DSC sample pans which avoid mass losses. Heat capacities before and after vulcanization were measured on the same samples using special DSC procedure and reversible thermal effects due to rubber components were corrected. For natural rubber vulcanized with sulfur at t=40…110 °C we found, in J/(kg S)−1 K−1: Δcp=76+11 t, whatever the temperature vulcanization between 100 and 160 °C.